Fact #1: Gluten is…
…a naturally occurring protein composite found primarily in wheat, rye and barley, as well as some types of oats. Gluten consists of gliadin and glutenin. Gliadin is one of the proteins that forms gluten. Doctors will test for anti-gliadin antibodies if celiac disease or gluten hypersensitivity is suspected. In celiac patients, the gliadin triggers immune response. Glutenin is the other protein comprising gluten. From a dietary view, gluten has only recently entered the human diet; it gives bread elasticity and strength. 
Fact #2: Not All Grains Contain Gluten
Corn, rice and certain types of oats do not contain gluten. These grains do not typically provoke a response in individuals with celiac disease or with gluten sensitivity.